Once operational, the alarm system shall remain dormant for a period of between 3 and 12 min (Td). At the end of this dormant period, the alarm system shall initiate a visual indication on the bridge.
First stage alarm
If not reset, the BNWAS shall additionally sound a first stage audible alarm on the bridge 15 s after the visual indication is initiated.
Second stage alarm
If not reset, the BNWAS shall additionally sound a second stage remote audible alarm in the back-up officer’s and/or Master’s location 15 s after the first stage audible alarm is initiated.
Third stage alarm
If not reset, the BNWAS shall additionally sound a third stage remote audible alarm at the locations of further crew members capable of taking corrective actions 90 s after the second stage remote audible alarm is initiated.
In vessels other than passenger vessels, the second or third stage remote audible alarms may sound in all the above locations at the same time. If the second stage audible alarm is sounded in this way, the third stage alarm may be omitted.
In larger vessels, the delay between the second and third stage alarms may be set to a longer value on installation, up to a maximum of 3 min, to allow sufficient time for the back-up officer and/or Master to reach the bridge.
Facilities shall be provided to inhibit the third stage alarm and to increase the delay between the second and third stage alarms to 3 min.
The reset function shall, by a single operator action, cancel the visual indication and all audible alarms and initiate a further dormant period. If the reset function is activated before the end of the dormant period, the period shall be re-initiated to run for its full duration from the time of the reset.